In Washington state, a new law requires a doctor's clearance before youth athletes who suffer a suspected concussion can resume play.

In Oregon, a new law mandates annual concussion training for coaches. School sports officials there keep players who suffer such head injuries off the field for the rest of the day and mandate a medical evaluation before they return. Similar rules now apply to pro football players.

But concussion regulations are looser in California, where a blow to the head during a Thanksgiving Day football game - the second, it appears - nearly killed San Jose High Academy running back Matt Blea.

Brain-injury experts and many parents say a growing body of medical evidence points to a need for tougher rules regarding concussions, which are caused by a blow or whiplash. Severe or repeated concussions can cause "second-impact syndrome," in which a subsequent blow before the first heals becomes fatal.

"There needs to be more done," said Paula Daoutis, administrative director of the California Brain Injury Association, which is scheduled to make a presentation to the state Legislature this month on the need for new laws.

"If you see a player take a hit on the head, you should take them off until they can be evaluated," Daoutis said. "When they get back in too soon and another concussion occurs, this is where more serious injuries are going to happen."

Sports-related head injuries have been much in the news over the past year, with new research highlighting the cumulative dangers of multiple concussions and congressional hearings on brain damage to National Football League athletes. Star University of California, Berkeley, tailback Jahvid Best was shelved after a Nov. 7 concussion, his second in eight days.

A study by the Center for Injury Research and Policy at Nationwide Children's Hospital in Columbus, Ohio, in 2009 found that 40.5 percent of high school athletes who suffer concussions return to play before it is safe to do so, with 16 percent of high school football players who lost consciousness returning to play the same day.

Medical research indicates that children's brains recover more slowly from concussions, making them more vulnerable to second-impact syndrome.

According to the Annual Survey of Football Injury Research, seven high schoolers were killed playing the game in 2008, a figure that does not include indirect fatalities such as heatstroke.

Five of the seven died from head injuries, two of which involved second-impact syndrome. One was a 16-year-old New Jersey linebacker who had not fully recovered from a concussion three weeks earlier. The other was a 16-year-old North Carolina player who had suffered a concussion during practice two days earlier.

Blea's family had no comment about his previous injury, which was disclosed by one of his doctors during a news conference, and they have praised the school's handling of the matter. School officials said they were unaware of a prior injury or when it might have occurred.

The National Federation of State High School Associations' 2008 concussion management guidelines state that "no athlete should return to play the same day of a concussion" and that they should receive clearance from a medical professional before resuming practice or competition. State school athletics organizations around the county base their policies on those guidelines, but they are simply recommendations.

The 2009 sports medicine handbook of the California Interscholastic Federation, overseeing athletic competition for nearly 1,500 state high schools, is more ambiguous about when a player with a suspected head injury may resume play. It says the player "should not be returned to practice/games until cleared by medical personnel" but does not require that in writing or mention a same-day restriction.

California law requires coaches to have valid first-aid certification, which CIF associate executive director Roger Blake said must be renewed every two to three years. But that training is not specific to concussions, something the federation now hopes to change.

The CIF in September launched a "play it safer" campaign to help coaches and players recognize concussion symptoms. But that effort stopped short of urging coaches to bench athletes for the day after suspected concussions.

Blake acknowledged that other states and even the NFL have stricter concussion rules than those for student athletes in California, where it is up to schools to decide how to implement CIF guidelines. He said his organization and the state are struggling to keep abreast of a rapidly evolving area of medicine and that most schools already go beyond the guidelines to avoid lawsuits.

"It's always best if have a uniform policy statewide for the health and safety of kids, and we don't have that now," Blake said. "That would definitely be an asset. But it's still going to come down to the coach, the school, the parents and teammates saying, 'Roger's not acting right' and someone turning him in."

The 32,000-student San Jose Unified School District, which includes Blea's school, requires any student athlete suffering an injury requiring medical attention to be symptom-free for a week and have a doctor's release before returning to play, said spokeswoman Karen Fuqua.

The new Washington state law is believed to be the nation's toughest concerning youth sports concussions. It was inspired by a 13-year-old middle school football player who suffered brain damage from a 2006 concussion.

The Oregon School Activities Association last year barred student athletes from playing for the rest of the day after a concussion and required a medical evaluation before they can return to the sport. Oregon also passed a law requiring annual training for school coaches in recognizing concussion symptoms, a move inspired by a high school footballer who suffered a permanent brain injury during a game.

A CIF-backed bill pending in the California Legislature, AB 533 by Assemblywoman Mary Hayashi, would add concussion training to the first-aid certification requirement for high school sports coaches.

But some parents say student athletes would benefit from stricter return-to-play rules, because even coaches and parents primed on concussion symptoms may not be the best judge of a player's recovery. And the extent of an injury may not be readily apparent at first.

Denise McCalla Creary of San Jose, whose son quit football at Harker School after a serious head injury last year, said it's hard for a parent to pull an eager kid from the game. She thinks having stronger standards would help ensure young players don't return too soon.

"If there are no rules," she said, "it's pretty much wide open. For parents who love the sports themselves, it's hard for them to tell their child no. It might help if an oversight organization established some policy, if it created rules and all the coaches had to follow that."